<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - Canvas Textured Cube</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js"
  }
}
</script>

<script type="module">
import * as THREE from 'three';

function main() {

	const canvas = document.querySelector( '#c' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );

	const fov = 75;
	const aspect = 2; // the canvas default
	const near = 0.1;
	const far = 5;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.z = 2;

	const scene = new THREE.Scene();

	const boxWidth = 1;
	const boxHeight = 1;
	const boxDepth = 1;
	const geometry = new THREE.BoxGeometry( boxWidth, boxHeight, boxDepth );

	const cubes = []; // just an array we can use to rotate the cubes
	const ctx = document.createElement( 'canvas' ).getContext( '2d' );
	ctx.canvas.width = 256;
	ctx.canvas.height = 256;
	ctx.fillStyle = '#FFF';
	ctx.fillRect( 0, 0, ctx.canvas.width, ctx.canvas.height );
	const texture = new THREE.CanvasTexture( ctx.canvas );

	const material = new THREE.MeshBasicMaterial( {
		map: texture,
	} );
	const cube = new THREE.Mesh( geometry, material );
	scene.add( cube );
	cubes.push( cube ); // add to our list of cubes to rotate

	function resizeRendererToDisplaySize( renderer ) {

		const canvas = renderer.domElement;
		const width = canvas.clientWidth;
		const height = canvas.clientHeight;
		const needResize = canvas.width !== width || canvas.height !== height;
		if ( needResize ) {

			renderer.setSize( width, height, false );

		}

		return needResize;

	}

	function randInt( min, max ) {

		if ( max === undefined ) {

			max = min;
			min = 0;

		}

		return Math.random() * ( max - min ) + min | 0;

	}

	function drawRandomDot() {

		ctx.fillStyle = `#${randInt( 0x1000000 ).toString( 16 ).padStart( 6, '0' )}`;
		ctx.beginPath();

		const x = randInt( 256 );
		const y = randInt( 256 );
		const radius = randInt( 10, 64 );
		ctx.arc( x, y, radius, 0, Math.PI * 2 );
		ctx.fill();

	}

	function render( time ) {

		time *= 0.001;

		if ( resizeRendererToDisplaySize( renderer ) ) {

			const canvas = renderer.domElement;
			camera.aspect = canvas.clientWidth / canvas.clientHeight;
			camera.updateProjectionMatrix();

		}

		drawRandomDot();
		texture.needsUpdate = true;

		cubes.forEach( ( cube, ndx ) => {

			const speed = .2 + ndx * .1;
			const rot = time * speed;
			cube.rotation.x = rot;
			cube.rotation.y = rot;

		} );

		renderer.render( scene, camera );

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

main();
</script>
</html>
